This invention relates to miniaturized devices for the controlled exposure or release of molecules such as drugs and/or secondary devices such as sensors.
Microchip devices for chemical and drug delivery and for controlled exposure of reservoir contents have been described in detail in U.S. Pat. No. 5,797,898; U.S. Pat. No. 6,123,861; PCT WO 01/64344; and PCT WO 01/35928. One group of embodiments of these microchip devices provides active release or exposure of the contents of a reservoir in the substrate of the device. “Active” is used to refer to those embodiments in which release or exposure is initiated at a particular time by the application of a stimulus to the device or a portion of the device.
An important application for these active microchip devices is to serve as an implantable device for the delivery of drugs in the body of humans and animals, for the treatment or diagnosis of disease. Due to its small size, the microchip device may be implanted in the body in a variety of locations, including, but not limited to, under the skin and in the peritoneal cavity. The device may also be ingested for drug delivery or content exposure throughout the gastrointestinal tract. Flexibility of implant location and site variation are particularly important, for example when local, rather than systemic, administration is desired. Currently available implantable drug delivery devices such as pumps may be too large for use in many of locations in the body.
U.S. Pat. No. 5,797,898 to Santini, et al., describes powering the active microchip devices using pre-charged power sources (e.g., pre-charged micro-batteries), which can be integrated with the microchip and its associated electronics. Such a pre-charged micro-battery can be a thin film battery fabricated on the microchip substrate itself, or it can exist as a separate component that is connected to the microchip substrate through interconnects and packaging. Such power sources generally must store all the power required during the operating lifetime of the microchip device. If it cannot store all of the required power during the intended useful life of the microchip device, then the depleted battery must be replaced with a new battery. However, such replacement typically is impractical or undesirable for an implanted device. It would therefore be advantageous to avoid the need for battery replacement. Furthermore, conventional means of powering an implantable device may be unsuitable for a variety of implanted devices, particularly for all possible implant locations.
U.S. Pat. No. 5,797,898 also describes incorporating a pre-programmed microprocessor into the active microchip device to control which reservoirs are activated and when they are activated. The microprocessor is disclosed as being fabricated onto the back of the microchip substrate. It would be advantageous to be able to alter the programming after implantation in order to make the microchip device more flexible and adaptable to various applications, particularly implant applications.
It is therefore an object of the present invention to provide devices and methods for reducing or eliminating the need for pre-charged power sources for active release microchip devices.
It is another object of the present invention to provide devices and methods for avoiding explantation of implanted microchip devices for the purpose of replacing or recharging the device's power source or for the purpose of reprogramming the device's microprocessor.
It is a further object of the present invention to provide additional means for powering and communicating with microchip drug delivery and sensing devices.
These and other objects, features, and advantages of the present invention will become apparent upon review of the following detailed description of the invention taken in conjunction with the drawings and the appended claims.